Our recent papers examine the soybean production system in Mato Grosso to determine its impacts on ecosystem quality and services, and biodiversity

As discussed in detail in previous posts, Mato Grosso is the largest soybean producer in Brazil. The region has been of interest to the research community as it has been home to an expanding agricultural frontier with well-document land use activity through the 2000s. Both agricultural expansion through deforestation, as well as intensification either through increased crop yield, or conversion of pasture into cropland have been observed in the Amazon and Cerrado biomes. Remote sensing has been a key tool in quantifying environmental impacts of land use change over time, with some attempts to identify impacts over the region as reported by greenhouse gas emissions, landscape fragmentation, etc.

Two papers published in the Journal of Cleaner Production (2017, 149, 680-689) and Environmental Science and Technology (2016, 50(21), 11769-11778) take a close look at the impacts of land use change for soybean production by focusing specifically on its production system. This work was performed using Life Cycle Assessment (LCA) a scientific method which aims at quantifying impacts of production systems by focusing on human health, ecosystem quality and natural resources end-point impacts. The difference with other impact assessment methods is the exclusive focus on what is called a “functional unit”, or in this case, “1 tonne of soybean produced in Mato Grosso in 2010” as described in our research.

UNEP/SETAC Life Cycle Initiativeguidelines published in 2013 introduced new methods to quantify impacts of land occupation and transformation on ecosystem services and biodiversity. According to the guidelines these services include: the soil’s ability to resist erosion (Erosion Resistance Potential, ERP); the soil’s ability to filter water through mechanical and physiochemical processes (Mechanical and Physiochemical Purification Potential, WPP-MF and WPP-PCF); regulation of freshwater through groundwater recharge (Freshwater Regulation Potential, FWRP); the soil’s ability to store carbon (Biotic Production potential), and the carbon regulation of soil and forest cover (Climate Regulation Potential, CRP). The 2013 recommendations for impact assessment on biodiversity, were updated in 2016 and serve as the only consensus based method for land use change impacts in the current UNEP/SETAC Life Cycle Initiative Global Guidance For Life Cycle Impact Assessment Indicators (Vol 1).

In Lathuillière et al. (2017), we show that results obtained using the LCA methods parallel findings already discussed in the literature by the earth sciences with respect to the carbon and the water cycles. This results was welcome because:

1-It means that some of the policies and initiative already in place in Brazil (e.g. Agricultural Carbon Credit Program, or plano ABC, the Federal Forest Code, etc.) apply in the context of the production system, meaning that actions can be taken following LCA results.

2-LCA results provide an additional perspective of impacts by focusing on the functional unit rather than the biome as a whole. For instance, the ecosystem services impacts of land transformation and occupation for soybean production in Amazonia represented $532 and $260 per tonne of soybean, respectively. These values can be compared against other production systems or other biomes (e.g. the Cerrado showed impacts of $ 231 and $253 per tonne of soybean, respectively) or can serve as a benchmark for reducing environmental impacts per tonne of soybean in other years.

Impacts obtained on the water cycle could be misleading when addressed on their own with the UNEP/SETAC guidelines. Since the guidelines consider groundwater recharge only, the impacts of soybean production show up mostly as a benefit to the environment due to increased groundwater recharge due to reduced land evapotranspiration. To fill this gap, we proposed an additional impact pathway in Lathuilliere et al. (2016) that takes into account the regional recycling of water vapour into precipitation (Precipitation Reduction Potential, PRP) with subsequent impacts on terrestrial ecosystems. As this atmospheric feedback is important in Amazonia, the combination of groundwater recharge with regional water vapour recycling provide a better picture of impacts of land transformation and occupation on the water cycle in Amazonia.

Our recent review suggests that cropland irrigation should be included in water management models at the agricultural frontier of Mato Grosso (Brazil) to elucidate possible future disruptions in Amazonia’s water cycle. Continue reading →